package binarytree;

import java.sql.Array;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

public class HuffmanTree {
    public static void main(String[] args) {
        int[] arr = {13, 7 ,8,3,29,6,1};
        Node root = createHuffmanTree(arr);
        preOrder(root);

    }

    public static void preOrder(Node root) {
        if(root!=null){
            root.preOrder();
        }else {
            System.out.println("树为空，无法遍历~");
        }
    }

    public static Node createHuffmanTree(int[] arr) {
        List<Node> nodes = new ArrayList<Node>();
        for(int value: arr) {
            nodes.add(new Node(value));
        }
        while(nodes.size()>1){
            Collections.sort(nodes);
            System.out.println("nodes = " + nodes);
            Node leftNode = nodes.get(0);
            Node rightNode = nodes.get(1);
            Node parent = new Node(leftNode.value + rightNode.value);
            parent.left = leftNode;
            parent.right = rightNode;
            nodes.remove(leftNode);
            nodes.remove(rightNode);
            nodes.add(parent);
        }
        return nodes.get(0);
    }
}

class Node implements Comparable<Node> {
    public int value;
    public Node left;
    public Node right;

    public Node(int value) {
        this.value = value;
    }

    //前序遍历赫夫曼树
    public void preOrder() {
        System.out.println(this);
        if (this.left != null)
            this.left.preOrder();
        if (this.right != null)
            this.right.preOrder();

    }

    @Override
    public String toString() {
        return "Node{" +
                "value=" + value +
                '}';
    }

    @Override
    public int compareTo(Node o) {
        return this.value - o.value;
    }
}
